1. Field of the Invention
The invention relates to a device for optimal coupling of light into at least one light conductor in an illuminating element in a vehicle exterior mirror or a vehicle rear view device, such as a camera, with limited installation space in a vehicle.
2. Description of the Related Art
Conventional exterior mirrors have a design allowing the mirror head to be folded backwards in relation to the mirror base, by hand or driven by a motor, in the direction of movement of the vehicle. In addition, the mirror glass bracket can normally be positioned in the mirror head from the inside of the vehicle. A perfect view is thus ensured for the driver, which results in better road safety. Many exterior mirrors comprise an indicator lamp, which is provided on the front side of the mirror housing in the direction of movement. For road users who are next to or behind the exterior mirror, the indicator lamp can generally not be seen, or only insufficiently. Therefore, additional LEDs which radiate along the direction of travel, are used, and are integrated on the outermost edge of the exterior mirror in the indicator.
According to ECE regulations, an additional indicator light in the exterior mirror should light up a region beginning from 5° from the longitudinal axis of the vehicle, up to 60° to the longitudinal axis of the vehicle in the opposite direction of movement. The light intensity in this region, which is regulated by law, is defined in the process and must be achieved.
A variety of solutions for indicators in the exterior mirror is known from the prior art. Here, indicator modules are integrated into the housing of an exterior mirror. According to the design, these indicator modules contain fibre optic cables, reflectors, printed circuit boards, lenses and cover glass and illuminants. LEDs are increasingly used as illuminants due to the known advantages.
In EP 1120312, an exterior mirror with an indicator is known, which comprises a light module, in which a variety of LEDs shine through openings of a reflector. The LED, which is located on the outermost edge of the exterior mirror, has a radiating direction, which corresponds to the legal regulations on the radiation characteristics. The beam-forming is produced by the reflector. The whole light module is clipped into the housing of the exterior mirror, and is electrically contacted by a plug connection. The construction of a lighting module for the indicator is time-consuming and expensive, since a variety of LEDs are attached along an elongated lighting module.
The use of light guide technology lends itself to illuminating an indicator in an exterior rear view mirror, since the installation space in the exterior rear view mirror is limited, and the light emission can be achieved aesthetically with a light conductor, whereby the coupling of the light takes place on an end surface of the light conductor.
EP0858932, for example, is to be named as the prior art, which describes a design of a light conductor in a light module for a mirror indicator. Differing embodiments are also suggested for coupling the light in the light conductor of the mirror indicator. The problem in this process is having enough light available at the end of the light conductor for fulfilling the legal requirements.
So-called TIR (Total Internal Reflection) lenses are also suggested for coupling the light. These TIR lenses comprise a variety of faceted structures, which internally reflect the light, and lead to parallelising the light as a result. A plane, flat light conductor is known in U.S. Pat. No. 5,806,955, into which the light is coupled by several TIR lenses, as well as an elongated light conductor, which comprises a TIR structure on its coupling surface.
US 20080291683 shows a TIR lens, of which the irradiation surface 20 includes and surrounds the dome-shaped lens of an LED. In the process, the TIR lens is attached above the level of the LED, as can also be seen in FIGS. 1 and 1A. In the schematic representation of FIG. 3, the irradiation point is also surrounded by 180 degrees.